Machine gun feed



Oct. 7, 1947. D, s, ELLIOTT 2,428,414

l MACHINE GUN FEED Filed June 13, 1941 2 Sheets-Sheet 1 v mwN X WW QN Oct. 7, 1947.

D. S. ELLIOTT MACHINE GUN FEED Filed June 13, 1941 2 Sheets-Sheet 2 I l' lll Patented Oct. 7, 1 947 MACHINE GUN FEED Daniel S; Elliott, Middle River, Md., assignor to The Glenn L. Martin Company, Baltimore, Md. Y

Application June 13, 1941, Serial No. 397,879

3 Claims. 1 This invention is directed to a power boost for feeding a belt of ammunition to a machine gun.

The ammunition for machine guns is conven- 2 The motor for actuating the sprocket wheels is automatically started or stopped in dependence upon the amount of pull exerted by the belt which in turn is pulled by the machine gun. When the tionally mounted in a belt which is pulled along motor is operated, the belt is driven by the by the machine gun itself to feed ammunition to sprockets at a speed greater than the maximum the machine gun. Diiiiculties are encountered, ring rate of the gun. If desired a series of mohowever, when the drum or roll of ammunition tors and sprockets may be placed in tandem and is located at some distance from the machine actuated by common control so that a belt of gun, as the weight of the belt between the drum lo long length may be fed from the ammunition and the machine gun becomes quite heavy and drum to the gun without producing more than the actuating mechanism of the machine gun is the desired load upon the gun. not powerful enough to draw the belt along as t A means by which the objects of this invention fast as it should move. As the belt slows in its are obtained is more clearly shown in the accomtravel the machine gun can not fire as rapidly l5 panying drawings in which: as before and therefore its firing power dimin- Fig. 1 is a side elevational View of' a mOtOr ishes, and in some instances the slowing of the driven sprocket for propelling au ammunition belt may cause the machine gun to jam. In airbelt; craft construction, in particular, it is desirable Fig- 2 is a plan View 0f Fig. 1; to locate the drum or drums of ammunition at 2o Fig. 3 is an end elevational view of Fig. 1; some distance from the machine gun and thus Fig. 4 is a diagrammatieal View illustrating the a relatively long path exists for a belt of amelectric Circuit fOr Operating tWO bOOSter units munition to travel from the drum to the gun. intandem; and

The object of the instant invention is to pro- Fig. 5 is a side elevational view illustrating vide a power boost for aiding the movement of the tWO bOOSter units mounted in tandembelt of ammunition as it passes from the drum Figure 6 is an enlarged fragmentary SeCtiOIlal to the gun, thereby making a relatively long belt View of the mounting of the SDIOCketS 011 the of ammunition possible without causing diidrive Shaftculties at the gun. Figure 7 is a section taken on the line 'l-'l of Another object of the invention is to construct Figure 6- a power boost mechanism which is automatically In Fig. 1, a machine gun diagrammatieally 11- brought into operation when the belt tends to lustrated at A, is fed with a belt of ammunition slow down in its movement from the drum to the B- Normally the machine gurl itself draws the gun. belt of ammunition into the machine gun. How- Another object of the invention is to produce a ever, when the ammunition drum C is located at booster unit for ammunition feed, which has a some distance from the machine gun, the drag mean rate of feed equal to the rate of feed proof the ammunition belt becomes too great for the vided by th'e automatic gun, and need not be machine gun to pull the belt alOng at a rate Sufsynchronized with the gun. cent to feed bullets to the gun as fast as the Another object of the invention is to take a 40 gun is capable of firing. considerable part of the drag load of the belt To aid in the feeding of an ammunition belt from the gun so that the gun can re at its maxithe novel booster unit of the instant invention mum firing rate. is employed. The ammunition belt B passes Another object of the invention is to produce through a bOX-Shaped tlOugh 2 Where either the a motor driven booster for facilitating the movebelt itself or the bullets in the belt are engaged ment of an ammunition belt, in which the rate by a pair of spaced sprocket wheels 4 and 6. A of ammunition feed is controlled in part by the leaf spring 8 on the bottom of trough 2 lifts the belt to start and stop intermittently the motor. belt from the trough to reduce friction there- Another object of the invention is to produce with and urges the ammunition belt into engagean all electric powered feed boost for machine ment with the teeth of the sprocket wheels, which guns. teeth project downwardly through slots in the Generally these objects of the invention are cover plate 3 into the trough. Aspring I 0, Fig. 2, obtained by providing motor driven sprocket mounted on the side of trough 2, holds the belt wheels engaging the belt of ammunition between in longitudinal position as it passes through the the ammunition drum and the machine gun. trough, it being noted that this spring is not 3 necessary if the trough is of proper width for the belt.

In the embodiment of the invention shown, the sprocket wheels are driven by an electric motor I2, the shaft of which is geared to the shaft I4 upon which the sprocket wheels are mounted. Motor I2 is mounted on top as shown, or on bottom of the trough 2 opposite spring 8, and is adapted to drive the sprockets at a speed greater than the maximum firing rate of the gun.

As the belt of ammunition leaves trough 2 it passes through a tubular shelf I6 which is hinged at I8 to the discharge end of the trough 2 so that the tubular shelf Mounted on the bottom of trough 2 near hinge I8 is an electric switch 2E) having a conventional push button 22 holding the switch in normal open position when the shelf I6 is down as illustrated in full lines in Fig. l.. An arm 24 depends' from the side of tubular shelf I6, this arm carrying an adjustable screw 25. The free end of this screw engages a leaf spring 28 supported at one end on trough 2, which in turn presses upon the push button 22 to keep the switch contacts normally open. In some instances, it is desirable to have motor I2 and the sprockets mounted on shelf I6 and swingable therewith.

The operation of this booster unit is as follows: As is illustrated in Fig. l, the machine gun is mounted above and substantially perpendicular to the shelf It. In general, th'e gun is positioned with respect to shelf I6 so that a pull on the belt will lift the shelf. Normally the ammunition belt B extends through aligned trough 2 and shelf I6 when shelf I6 is in its down position. When the gunner depresses the trigger-on the gun and the gun begins firing, the ammuni-y tion belt and shelf I begin to rise toward the position shown in dotted lines, Fig. 2, this being because of the drag on the belt. As shelf I6 moves, the arm 24 moves screw 26 away from the spring 28, push button 22 thus moving outwardly to close the switch' and to startmotor I2. Sprockets 4 and 6 are thereupon put inmotion by motor I2 and drive the ammunition belt forwardly. Shelf It continues to rise under the pull of the belt as the sprocket wheels 4 and B pick up speed, this rising continuing until the speed of wheels4 and 8 equals the rate-of feed to the gun. Thereafter the motor feeds the ammunition belt faster than the shells are consumed-by the gun, and accordingly slack is created in the ammunition belt between the sprocket wheels and machine gun A, this causing thel shelf I6 to drop, and the cycle begins again. Consequently the rate offeed of the bullets to thegun` is controlled by the booster unit, whichin turn is controlled by the pull of the ammunition belt on the shelf, the motor being started or stopped by the shelf movement. 'Ihe maximumv Speed of the` sprockets driven by their motor is always greater than the maximum firing rateof the gun. By this means itis insured that bullets are available for the machine gun at all-times. Furthermore, the booster unit moves the belt at a mean speed substantially equal to that of the machine gun feed, and without necessarily being synchronized with the machine gun feed. In order to avoid a braking action on the part of the motor if the motor should jam, or the motor circuits should fail, overrunning clutches of conventional design can be. includedY between the sprocket wheels and their supporting shaft. This eliminates. the possibility of stoppage ofthemachine Iii can rotate upwardly.v

operative. Such a, clutch is illustrated in Figures 6 and 7. Figure 6 shows an enlarged sectional view of the hub of sprocket 6 mounted on shaft I4. Sprocket 6 is free to rotate on shaft I4 and as will be seen from Figure '7, and includes a one way friction clutch to cause sprocket 6 to be driven by shaft I4. This clutch mechanism consists of a plate 49 secured to rotate with shaft I4 having a ange portion 4I extending around portion 42 of the hub of sprocket 6. The periphery of portion 42 is formed with eccentric surfaces 43 that form with the inner wall of member 4I, a tapered channel. Pockets 44 are formed at the larger ends of the tapered channels. Balls 45 are placed in the channels and are of such a diameter that when in the pocket or the enlarged end of the channel, they have considerable clearance but their diameter must be more than the narrow end of the tapered channel. It can be seen from a consideration of Figures 6 and 7 that sprocket 6, which is secured to and turns with member 42, can rotateV freely in a counterclockwise direction when the shaft I4 and flange 4I remain stationary, but when the motor drives shaft I4 and flange 4I, the balls will be wedged between member 42 and 4I in the tapered channel and for counterclockwise rotation, sprocket will be driven by shaft I4. When shaft I4 stops, sprocket 6 may continue to move because the balls 45 will move toward the enlarged end of the channel or the pockets 44 out of frictional enga-gement with members 4I and 42. This type of mechanism is often referred to as a one-way clutch because sprocket yl may freely move in a clockwise (see part 42 in Figure '7) direction relative to shaft I4 but is prevented from moving iin a counterclockwise (see part 42 in Figure 7) direction when shaft I4 remains stationary,

When the ammunition belt must travel an unusually long distance from the `ammunition drum to the machine gun, two motor driven sprocket units SII and 32 may be placed upon a trough 34 as illustrated in Fig. 5. A swingable shelf 32B actuates a switch 38 exactly as described for Figs. 1 to 3. As shown in Fig. 4, switch' 38 is connected in parallel to motor-units 3G and 32 so that both motors are simultaneously controlled by switch 38.

The-invention therefore provides'a means for posi-tively driving the ammunition belt from the Vammunition drum to the machine gun so that ammunition is always available for the machine gun, and no undue .pull such as would result in slowing down'or stoppage of the machine gun can occur because of the length of the travel between the ammunition drum and the machine gun. The operation of the booster unit is automatic and dependent upon the rate of feed demanded by the machine gun. It is to be understood that the power boost disclosed can be used for automatic guns of all calibers, including automatic cannons. Y

Having lnow described the means 'by which the objects of the invention are obtained, I claim:

l. A power booster for the ammunition belt of .a machine gun comprising a hollow trough through which said belt of ammunition is adapted toimove .an electric motor and a control circuit therefor, a ysprocket wheel driven by said motor mounted upon said trough with theteeth of said v.sprocket wheel projecting into said trough to engagersaid ammunition, a hollow member .through which the ammunition is adapted to move, hinged to and Een even Vthough the booster 11n-it beameinli- 75 normally aligned with said trough, said hollow member being adapted to be moved out of alignment by the belt when the gun exerts a tension on said belt, and an electric switch to control said motor circuit, said switch being mounted for actuation by movement of said hollow member from the normal position upon tensioning of said belt whereby said motor is energized to furnish additional power to move said belt simultaneously with the action of said gun on said belt.

2. In a machine gun feed device, a power booster for an ammunition belt, said booster comprising a hollow trough through which said belt of ammunition is adapted to move, said trough having an end section thereof, adapted to be positioned adjacent thegun, hinged with respect to the remainder of said trough, an electric motor and a control circuit therefor, a sprocket wheel driven by said motor and mounted upon said trough with the teeth of said sprocket wheel projecting into said trough to engage said belt of ammunition, said hinged portion being adapted to be moved relative to the remainder of said trough by the belt of ammunition when the gun exerts a tension on said belt, and an electric switch in said circuit to control said motor, said switch being mounted on said device for actuation by movement of said hinged section of the trough from the normal position upon tensioning of said belt whereby said motor is energized to furnish additional power to move said belt simultaneously with the action of said gun on said belt.

3. In combination, an automatic gun, a belt of ammunition, means operated by the automatic 6 action of the gun for pulling the belt toward the gun, a track to guide the belt, and a booster unit for moving the belt in the track; said unit com- .prising a sprocket Wheel arranged to engage said belt, a motor to drive said sprocket wheel, means to actuate the motor in response to the tension in the belt created by the firing of the gun, said motor and sprocket wheel being mounted to maintain the sprocketl wheel in the path of the belt, and an overrunning clutch between the motor and the sprocket wheel so constructed and arranged that the belt may be advanced by the automatic action of the gun independent of the motor.

DANIEL S. ELLIOTT.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,907,342 Capell May 2, 1933 1,842,446 Dabrasky Jan. 26, 1932 FOREIGN PATENTS Number Country Date 690,426 France June 17, 1930 486,684 Great Britain June 9, 1938 366,247 Italy Dec. 22, 1938 373,677 Italy Aug. 1, 1939 502,948 Great Britain Mar. 28, 1939 193,950 Switzerland Feb. 1, 1938 

